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      函数进阶
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        <h2 id="6-函数进阶"><a href="#6-函数进阶" class="headerlink" title="6.函数进阶"></a>6.函数进阶</h2><h4 id="1-您知道什么是闭包吗？"><a href="#1-您知道什么是闭包吗？" class="headerlink" title="1.您知道什么是闭包吗？"></a>1.您知道什么是闭包吗？</h4><p>​    闭包就是内外层函数的嵌套，内部函数引用外部函数的局部变量，外部函数返回内部函数。</p>
<p>​    <strong>优点：使变量延续下去</strong></p>
<p>​    <strong>缺点：比较浪费内存空间</strong></p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">def</span> <span class="title">outer</span>():</span></span><br><span class="line">    b = <span class="number">2</span></span><br><span class="line">    <span class="function"><span class="keyword">def</span> <span class="title">inner</span>():</span></span><br><span class="line">        print(b)</span><br><span class="line">    <span class="keyword">return</span> inner</span><br><span class="line">func = outer()</span><br><span class="line">print(func)</span><br><span class="line"></span><br><span class="line"><span class="comment"># 该outer函数内部封装了一个inner闭包函数</span></span><br></pre></td></tr></table></figure>
<h4 id="2-您知道什么是装饰器吗？"><a href="#2-您知道什么是装饰器吗？" class="headerlink" title="2.您知道什么是装饰器吗？"></a>2.您知道什么是装饰器吗？</h4><p>​    装饰器利用了闭包的原理，主要是用来对一个函数在不改变原有的功能的情况下额外增加新的功能。函数的返回值也是一个函数。</p>
<p>​    装饰器有三种类型：普通装饰器、被装饰函数带参数、装饰器带参数</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment"># 通常装饰器多用于对请求token进行解析</span></span><br><span class="line"><span class="function"><span class="keyword">def</span> <span class="title">make_token</span>(<span class="params">func</span>):</span></span><br><span class="line">    <span class="function"><span class="keyword">def</span> <span class="title">inner</span>(<span class="params">request, *args,**kwargs</span>):</span></span><br><span class="line">        token = request.META.get(<span class="string">&#x27;HTTP_AUTHORIZATION&#x27;</span>)</span><br><span class="line">        uid = jwt.decode(token, SECRET_KEY, algorithms=<span class="string">&#x27;HS256&#x27;</span>)[<span class="string">&#x27;uid&#x27;</span>]</span><br><span class="line">        <span class="comment"># 根据请求方式不同对token进行不同的解析</span></span><br><span class="line">        <span class="keyword">if</span> request.method == <span class="string">&quot;POST&quot;</span>:</span><br><span class="line">            request.data[<span class="string">&#x27;user&#x27;</span>] = uid</span><br><span class="line">        request.uid = uid</span><br><span class="line">        <span class="keyword">return</span> func(request, *args,**kwargs)</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> inner</span><br></pre></td></tr></table></figure>
<h4 id="3-说说您对递归的理解？"><a href="#3-说说您对递归的理解？" class="headerlink" title="3.说说您对递归的理解？"></a>3.说说您对递归的理解？</h4><p>​    调用函数的时候，直接或间接调用函数的本身这个过程就叫做递归。但是为了避免递归进入死循环，使用递归必须有一个递归条件出口。</p>
<h4 id="4-递归实现斐波那契数列"><a href="#4-递归实现斐波那契数列" class="headerlink" title="4.递归实现斐波那契数列"></a>4.递归实现斐波那契数列</h4><figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">def</span> <span class="title">func</span>(<span class="params">n</span>):</span></span><br><span class="line">    <span class="keyword">if</span> n == <span class="number">1</span> <span class="keyword">or</span> n == <span class="number">2</span>:</span><br><span class="line">        <span class="keyword">return</span> <span class="number">1</span></span><br><span class="line">    <span class="keyword">return</span> func(n-<span class="number">1</span>)+func(n-<span class="number">2</span>)</span><br></pre></td></tr></table></figure>
<h4 id="5-您知道函数参数的传值传引用吗？"><a href="#5-您知道函数参数的传值传引用吗？" class="headerlink" title="5.您知道函数参数的传值传引用吗？"></a>5.您知道函数参数的传值传引用吗？</h4><p><strong>python中函数传参都是传引用</strong></p>
<p>传递不可变数据类型的值在函数内部无法直接修改，类似于C</p>
<p>传递可变数据类型的值在函数内部可以直接修改，并且原始数据也会改变。传引用是将内存地址作为参数传递，形参和实参是同一个引用对象，因此形参修改后实参也会发生改变</p>
<p><strong>传递不可变数据为传值，传递可变数据为传引用</strong></p>

      
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